1. Field of the Invention
The invention relates to a transponder for transmitting processed data to a base station comprising memory means from which data may be read out, and including data processing means which may be brought to a normal-energy operating mode in a transmit mode of the transponder and may be brought to an energy-saving mode in a transmit mode of the transponder, and to which data processing means may be applied data read out from the memory means to process the data and by which data processing means processed data may be delivered, and including transmission means by which the processed data corresponding to the processed data delivered by the data processing means can be transmitted to the base station.
2. Description of the Related Art
Such a transponder as defined in the opening paragraph is known, for example, from document EP 0 534 559 A1. This known transponder is not only arranged and suitable for transmitting but also for receiving data. With the known transponder, data read out from the memory means are processed in the data processing means in two transmit modes of the transponder, and processed data are fed to the transmission means for transmitting the processed data to a base station. In a first transmit mode, the data processing means, which are formed by a microcomputer in the known transponder, are brought to a normal-energy mode of operation in which they are driven with a relatively high clock frequency, so that the relatively high processing rate of the data processing means is achieved at which the data processing means, however, have a relatively high energy consumption. In a second transmit mode, the data processing means are brought to an energy-saving mode of operation in which the data processing means are driven with a relatively low clock frequency and therefore have a relatively low energy consumption, as a result of which a relatively large transmission range with the transponder to a base station is achieved. In this manner, a relatively large transmission range is achieved, it is true, but the data transmission of the processed data from the known transponder to a base station is effected at only a low data transfer rate because the data processing means in the energy-saving mode process the data only very slowly, so that, unfortunately, there is a relatively long data transmission period.
It should be noted that in the known transponder there is a third possibility of a transmit mode in which data may be transmitted at a high data transfer rate over a relatively large transmission range, but in which the data processing means formed by the microcomputer are not activated at all, so that data read out from the memory means cannot possibly be processed, for example, be encoded or checksums cannot be added to the data for the purpose of enhancing the data transmission security. In this third transmit mode of the known transponder, only an interface device is activated in lieu of the data processing means with which interface device it is only possible to read data from a memory and apply them to a transmission coil which is additionally necessary for carrying out this third transmit mode and thus represents additional expenditure.